As investigators continue to study the use of drugs such as remdesivir for the treatment of the COVID-19 pandemic, some researchers are considering drug repurposing as a temporary solution.
As investigators continue to research the efficacy and safety of drugs such as remdesivir for the treatment of the coronavirus disease 2019 (COVID-19) pandemic, some researchers are considering drug repurposing as a temporary solution.
There are some notable limitations to drug repurposing, including patent barriers, complex regulatory pathways, and a lack of funding opportunities. With a new drug approval for COVID-19 potentially months away, researchers are hopeful that an already-approved drug may prove effective.
Researchers from the Pan American Journal of Public Health searched the government clinical trials database and found more than 80 clinical trials testing various coronavirus treatments, including both novel and repurposed drugs. They identified 19 studies at clinical trial phases 2, 3, or 4.
Chloroquine and hydroxychloroquine have been of particular interest for their antiviral effects against HIV. In HIV, the drugs work by inhibiting the virus’ entry into host cells. Preliminary findings among patients with COVID-19 have found similar efficacy. A recent trial found that 100% of patients treated with hydroxychloroquine in combination with azithromycin were virologically cured, compared with 57.1% of patients treated with hydroxychloroquine alone and 12.5% of patients in the control group.
Immunoglobulins have been found useful in several diseases, including idiopathic thrombocytopenia purpura, Guillain-Barre Syndrome, and multiple neurological autoimmune disorders refractory to standard immunosuppressive treatments. One trial is currently investigating human immunoglobulin in patients with pneumonia caused by COVID-19.
Several anti-influenza drugs are also being investigated, including umifenovir, oseltamivir, and favipiravir. Umifenovir is currently approved in Russia and China for the influenza virus and is patented for severe acute respiratory syndrome (SARS), whereas oseltamivir is approved for influenza A and B treatment. Favirpiravir is a nucleoside analog broad-spectrum antiviral drug and has shown efficacy against SARS-CoV-2.
Umifenovir is being investigated in a study comparing the drug with standard of care treatments, while 3 other studies are comparing the drug’s effects in combination with oseltamivir, lopinavir-ritonavir, and carrimycin, respectively.
Finally, the HIV protease inhibitor combination lopinavir and ritonavir has been of particular interest. In combination with b-1b interferon, lopinavir-ritonavir is in a phase 2 trial for the treatment of Middle East respiratory syndrome, a close relative of COVID-19. Several trials are investigating lopinavir-ritonavir treatments in comparison with the use of other drugs for COVID-19, including umifenovir, carrimycin, danoprevir-ritonavir, and interferon inhalation.
The hydroxychloroquine-azithromycin combination was the first repurposed drug to have promising results in clinical trials against COVID-19, but the authors noted that more extended studies are necessary to confirm the results.
Rosa S and Santos W. Clinical trials on drug repositioning for COVID-19 treatment. Pan American Journal of Public Health. 2020;44:e40. https://iris.paho.org/handle/10665.2/51949